OBJECTIVE: The overall objective of the proposed research is to: (a) acquire significant information on the mechanisms related to, and the role played by: dietary components, intestinal microflora and their metabolites on the etiology of colon cancer in man, (b) identify specific environmental and dietary components that either directly cause colon cancer or indirectly promote the formation and development of colon neoplasms, and (c) develop key biochemical and/or microbial indicators which distinguish low- and high-risk populations for colon cancer. APPROACH: The proposed study will determine: the fecal cholesterol and bile acid metabolites and fecal bacterial 7 alpha-dehydroxylase, cholesterol dehydrogenase and nuclear dehydrogenase activities and fecal bacterial transnitrozation reaction in members of high-risk cancer families, patients with familial polyposis and healthy controls consuming a mixed-Western diet. We also continue the present study in determining the metabolic activity of fecal microflora (above enzyme parameters) in patients with colon cancer and adenomatous polyps to permit an evaluation of these discriminants for colon cancer. In addition, we propose to isolate and identify the mutagens (presumptive carcinogens) in the feces of above study populations.